Light-activated treatments may solve MRSA problems after surgery

Health

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Published: Wednesday, September 10, 2008, 19:01 [IST]

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Washington, Sept 10 : Researchers from University College London, UK have suggested that using near infrared light along with killer dyes that can wipe out bacteria could effectively kill superbug problems faced by surgical patients.

The study led by Dr Ghada Omar showed that 99 pct of the potentially dangerous Staphylococcus aureus bacteria in infected wounds can be killed using a green dye that releases toxic molecules when it is activated by near-infrared light.

Near-infrared light is commonly used in fibre-optics and telecommunications because it passes through glass easily.

The dye used, called indocyanine green, is harmless to humans and inactive in the dark. However, it gives off toxic molecules that rapidly kill the bacteria when it is triggered by the right light wavelengths.

"The chemicals produced when the dye is activated harm the bacteria in such a wide variety of ways that it is unlikely bacteria could ever develop resistance to the treatment," said Dr Omar.

"This makes it ideal - and possibly the only option - for treating infections with multiple drug resistant bacteria, including MRSA," he added.

The new light-activated antimicrobial treatment is less effective when there are low oxygen levels in the infected tissues. This is a common problem in injuries where blood systems have been damaged, or where the injury is further away from the bodies' main vascular systems.

The new study showed that even with very low oxygen levels in the damaged tissues, most dangerous bacteria can still be killed using the light-activated dyes.

"Increasing oxygen levels in the infected tissues would maximise the killing effect", said Dr Omar.

"But even with low oxygen levels a very wide range of bacteria were killed, including over 70percent of Streptococcus pyogenes," he added.

The findings were reported at the Society for General Microbiology's Autumn meeting in Dublin.